Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

A decodable indicia reading terminal can comprise a housing including a
housing window, a multiple pixel image sensor disposed within the
housing, an imaging lens configured to focus an image of decodable
indicia on the image sensor, an optical bandpass filter disposed in an
optical path of light incident on the image sensor, an analog-to-digital
(A/D) converter configured to convert an analog signal read out of the
image sensor into a digital signal representative of the analog signal,
and processor configured to output a decoded message data corresponding
to the decodable indicia by processing the digital signal.

Claims:

1. A decodable indicia reading terminal comprising: a housing including a
housing window; a multiple pixel image sensor disposed within said
housing; an imaging lens configured to focus an image of decodable
indicia on said image sensor; an optical bandpass filter disposed in an
optical path of light incident on said image sensor, said optical
bandpass filter configured to pass light of two or more selected ranges
of wavelengths and to attenuate light of wavelengths outside of said two
or more selected ranges; an analog-to-digital (A/D) converter configured
to convert an analog signal read out of said image sensor into a digital
signal representative of said analog signal, said analog signal
representative of light incident on said image sensor; and a processor
configured to output a decoded message data corresponding to said
decodable indicia by processing said digital signal.

2. The optical indicia reading terminal of claim 1 configured to acquire
images in a monochrome mode and in a color mode.

3. The optical indicia reading terminal of claim 1, wherein said optical
bandpass filter is disposed between said housing window and said imaging
lens.

5. The optical indicia reading terminal of claim 1, wherein said optical
bandpass filter is disposed at a surface of said imaging lens assembly.

6. The optical indicia reading terminal of claim 1, wherein said multiple
pixel image sensor comprises a micro-lens; and wherein said optical
bandpass filter is disposed at a surface of said micro-lens.

12. The optical indicia reading terminal of claim 1, further comprising
one or more illumination LEDs configured to illuminate a substrate
bearing decodable indicia.

13. The optical indicia reading terminal of claim, 1 further comprising
one or more illumination LEDs having different spectral characteristics,
said one or more illumination LEDs configured to illuminate a substrate
bearing decodable indicia.

14. The optical indicia reading terminal of claim 1, further comprising
one or more illumination LEDs, each illumination LED of said one or more
illumination LEDs comprising one or more dies having different spectral
characteristics; wherein said one or more illumination LEDs are
configured to illuminate a substrate bearing decodable indicia.

15. The optical indicia reading terminal of claim 1, further comprising
one or more illumination LEDs configured to illuminate a substrate
bearing decodable indicia, by emitting light having an illumination light
spectrum; wherein said illumination light spectrum varies at different
areas of said substrate.

16. The optical indicia reading terminal of claim 1 further comprising
one or more illumination LEDs configured to illuminate said substrate, by
emitting light having an illumination light spectrum; wherein a center
wavelength of said optical bandpass filter is configured to match said
illumination light spectrum.

17. The optical indicia reading terminal of claim 1, wherein said optical
bandpass filter includes a passband configured to match a backlight
emitted by a portable communication device.

18. The optical indicia reading terminal of claim 1, wherein said housing
is provided by a hand held housing.

19. The optical indicia reading terminal of claim 1, wherein said housing
is provided by a point-of-sale workstation housing.

20. The optical indicia reading terminal of claim 1, wherein said housing
is provided by a presentation housing.

[0002] The use of optical indicia, such as bar code symbols, for product
and article identification is well known in the art. Decodable indicia
reading terminals are available in multiple varieties. For example,
minimally featured bar code reading terminals devoid of a keyboard and
display are common in point of sale applications. Decodable indicia
reading terminals devoid of a keyboard and display are available in the
recognizable gun style form factor having a handle and trigger button
(trigger) that can be actuated by an index finger. Decodable indicia
reading terminals having keyboards and displays are also available.
Keyboards and display equipped decodable indicia reading terminals are
commonly used in shipping and warehouse applications, and are available
in form factors incorporating a display and keyboard. In a keyboard and
display equipped decodable indicia reading terminal, a trigger button for
actuating the output of decoded messages is typically provided in such
locations as to enable actuation by a thumb of an operator. Keyboard and
display equipped decodable indicia reading terminals are available in a
form in which the keyboard and display are commonly provided by a display
having an associated touch panel. Decodable indicia reading terminals in
a form devoid of a keyboard and display or in a keyboard and display
equipped form are commonly used in a variety of data collection
applications including point of sale applications, shipping applications,
warehousing applications, security check point applications, and patient
care applications. Decodable indicia reading terminals are also available
in a presentation reader form factor. Such terminals can be mounted at a
checkout station. Some bar code reading terminals are adapted to read bar
code symbols including one or more of one-dimensional (1D) bar codes, and
two-dimensional (2D) bar codes.

[0003] One common type of scan engine found in hand-held and retail
scanners is the digital imager, which includes 1D (linear) imagers and 2D
(area) imagers. Digital imagers typically utilize a lens to focus the
image of the bar code onto a multiple pixel image sensor, which often is
provided by a CMOS-based or CCD-based image sensor that converts light
signals into electric signals. A light source such as light emitting
diodes (LEDs) simultaneously illuminate all of the bars and spaces of a
bar code symbol in order to capture an image for recognition and decoding
purposes.

SUMMARY OF THE INVENTION

[0004] In one embodiment, there is provided a decodable indicia reading
terminal which can comprise a housing including a housing window, a
multiple pixel image sensor disposed within the housing, an imaging lens
configured to focus an image of decodable indicia on the image sensor, an
optical bandpass filter disposed in an optical path of light incident on
the image sensor, an analog-to-digital (A/D) converter configured to
convert an analog signal read out of the image sensor into a digital
signal representative of the analog signal, and a processor configured to
output a decoded message data corresponding to the decodable indicia by
processing the digital signal. The optical bandpass filter can be
configured to pass light of two or more selected ranges of wavelengths
and to attenuate light of wavelengths outside of said two or more
selected ranges.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The features described herein can be better understood with
reference to the drawings described below. The drawings are not
necessarily to scale, emphasis instead generally being placed upon
illustrating the principles of the invention. In the drawings, like
numerals are used to indicate like parts throughout the various views.

[0009] In an illustrative embodiment, shown in FIG. 1, there is provided
an optical indicia reading terminal 100 including a housing 52 comprising
a head portion 54 and a handle portion 56, the latter further comprising
a hand grip 58 and a trigger 60. The trigger 60 can be used to initiate
signals for activating frame readout and/or certain decoding processes.
Other components of the optical indicia reading terminal 100 can be
disposed within the housing 52. For example, an image sensor 62 can be
disposed in the head portion 54 behind a housing window 63. The image
sensor 62 can be configured to output an electrical signal representative
of light incident on the image sensor.

[0010] The optical indicia reading terminal 100 can further comprise an
I/O interface which in the illustrative embodiment of FIG. 1 can be
communicatively coupled to a wired connection 66. The I/O interface can
be used to communicatively couple the optical indicia reading terminal
100 to a companion device 68 such as a register and/or peripheral data
capture devices in a point-of-sale (POS) application. Other
configurations of the I/O interface may utilize wireless communication
technology and/or contact-type features that do not require wires and/or
wired connection 66. In certain applications of the indicia reading
terminal 100 for example, the companion device 68 may be provided by a
docking station with corresponding mating contacts and/or connectors that
are useful to exchange power and data, including image data captured by
the imaging module 62.

[0011] Although not incorporated in the illustrative embodiment of FIG. 1,
the optical indicia reading terminal 100 can also comprise a number of
peripheral devices, including a display for displaying such information
as image frames captured by the terminal, a keyboard, and a pointing
device.

[0012] The optical indicia reading terminal 100 can be used, for example,
for bar code reading and decoding in POS and other applications. A
skilled artisan would appreciate the fact that other uses of optical
indicia reading terminal 100 are within the scope of this disclosure.

[0013] A product having decodable indicia can be scanned by the optical
indicia reading terminal 100. As used herein, "decodable indicia" is
intended to denote a representation of a message, such as the
representation in a bar code symbology of a character string comprising
alphanumeric and non-alphanumeric characters. Decodable indicia can be
used to convey information, such as the identification of the source and
the model of a product, for example in a UPC bar code that comprises
twelve encoded symbol characters representing numerical digits. The
optical indicia reading terminal can be configured to output a decoded
message data corresponding to the decodable indicia.

[0014] While FIG. 1 illustrates a hand held housing, a skilled artisan
would appreciate the fact that other types and form factors of terminal
housings are within the scope of this disclosure. For example, in one
embodiment schematically shown in FIG. 2, the decodable indicia reading
terminal can be incorporated into a POS workstation with a presentation
housing. The workstation 1010 can include a horizontal countertop 1012
for placement of products to be scanned. A bioptic scanner 1014 mounted
within the countertop 1012 can include a first housing portion 1016 and a
second housing portion 1018 which can project from one end of the first
housing portion in a substantially orthogonal manner. In one embodiment,
the first housing portion 1016 can comprise a laser-based indicia
scanning terminal and the second housing portion 1018 can comprise an
imager-based terminal. The countertop 1012 can include an optically
transparent (e.g., glass) horizontal-scanning window 1020 mounted flush
with the checkout counter, covered by an imaging window protection plate
1022 which can be provided with a pattern of apertures 1024a. The second
housing portion 1018 can further include a vertical-scanning window 1026
behind which an imager-based indicia reading terminal 1028 can be housed.
A skilled artisan would appreciate the fact that other ways of disposing
the scanners and scanning windows are within the scope of this
disclosure.

[0015] In POS and many other applications, one of the key challenges for
imaging devices is the requirement of intense illumination. The magnitude
of illumination intensity is directly correlated to the motion tolerance
performance of the bar code scanning/imaging device. Device's user
satisfaction depends on high motion tolerance demonstrated by the device,
while requiring the lowest possible perceived illumination intensity.

[0016] In order to reduce the perceived illumination intensity, the
housing window of a bar code scanning/imaging device can be configured to
only pass the light in the red spectrum region. The benefits of such
approach would include more stable exposure and more balanced images.
However, a red housing window would attenuate the light in other
(non-red) spectrum regions, thus producing a monochrome image and
potentially causing loss of image content. A clear housing window, on the
other hand, would pass all the color spectrum unfiltered but will lead to
a more intense perceived illumination.

[0017] In order to overcome the above described challenge, the optical
indicia reading terminal can in one embodiment comprise an optical
bandpass filter disposed in an optical path of light incident on the
image sensor and configured to balance the color content and the
perceived illumination. In one embodiment, the optical bandpass filter
can be configured to pass light of one or more selected ranges of
wavelengths and to attenuate light of wavelengths outside of the selected
ranges. In another embodiment, the optical indicia reading terminal can
comprise a multi-band optical bandpass filter that can be configured to
pass light of two or more selected ranges of wavelengths and to attenuate
light of wavelengths outside of the selected ranges. An optical indicia
reading terminal having a multi-band optical bandpass filter can be used
for both monochrome and color applications.

[0018] FIG. 3 illustrates a block diagram of one embodiment of an optical
indicia reading terminal. The optical indicia reading terminal 100 can
comprise a multiple pixel image sensor 62, which in one embodiment can be
provided by a charge-coupled device (CCD) image sensor. In another
embodiment, the image sensor 62 can be provided by a complementary
metal-oxide-semiconductor (CMOS) image sensor. A skilled artisan would
appreciate the fact that other types of image sensors are within the
scope of this disclosure.

[0019] The image sensor 62 can comprise a multiple pixel image sensor
array 3074 having pixels arranged in rows and columns of pixels, column
circuitry 3076, and row circuitry 3078. Associated with the image sensor
62 can be amplifier circuitry 3080, and an analog-to-digital (A/D)
converter 3082 which can be configured to convert image information in
the form of analog signals read out of multiple pixel image sensor array
3074 into image information in the form of digital signals. Also
associated with the image sensor 62 can be timing and control circuit
3084 for use in controlling, e.g., the exposure period of image sensor
62, and/or gain applied to the amplifier 3080. The noted circuit
components 62, 3080, 3082, and 3084 can be packaged into a common image
sensor integrated circuit 3086. In one example, image sensor integrated
circuit 3086 can be provided by an MT9V022 image sensor integrated
circuit available from Micron Technology, Inc. In another example, image
sensor integrated circuit 3086 can incorporate a Bayer pattern filter.

[0020] In operation, image signals can be read out of image sensor 62,
converted and stored into one or more memories such as RAM 3090. A memory
3092 can include RAM 3090, a nonvolatile memory such as EPROM 3094, and a
storage memory device 3096 such as may be provided by a flash memory or a
hard drive memory.

[0021] In one embodiment, the optical indicia reading terminal 100 can
include a processor 3088 which can be configured to read out image data
stored in memory 3092 and subject such image data to various image
processing algorithms. In one embodiment, the processor 3088 can be
configured to output a decoded message data corresponding to scanned
decodable indicia by processing a digital signal representative of an
analog signal read out of the image sensor 62.

[0022] Optical indicia reading terminal 100 can also include a direct
memory access unit (DMA) 3098 for routing image information read out from
image sensor 62 that has been subject to conversion to RAM 3090. In
another embodiment, the optical indicia reading terminal 100 can employ a
system bus providing for bus arbitration mechanism (e.g., a PCI bus) thus
eliminating the need for a central DMA controller. A skilled artisan
would appreciate that other embodiments of the system bus architecture
and/or direct memory access components providing for efficient data
transfer between the image sensor 62 and RAM 3090 are within the scope of
this disclosure.

[0023] The optical indicia reading terminal 100 can also include an
imaging lens assembly 3100 for focusing an image of the decodable indicia
1032 onto image sensor 62. Imaging light rays can be transmitted about an
optical axis 3102. The optical indicia reading terminal 100 can also
include an illumination assembly 3104 comprising one or more illumination
light source banks 3106 comprising one or more LEDS for generating an
illumination pattern substantially corresponding to the field of view of
the image sensor 62.

[0024] In one embodiment, each illumination LED can be formed by multiple
dies having different spectral characteristics. In another embodiment,
one or more illumination LEDs can have different spectral
characteristics. Hence, the spectrum of the light irradiated upon the
optical indicia can be formed by multiple different dies with different
spectral characteristics on a single LED, or by multiple LEDs with
different spectral characteristics. In a further aspect, the spectrum of
the light irradiated upon the indicia can vary at different area of the
indicia.

[0025] In one embodiment, the optical indicia reading terminal 100 can
also include an aiming pattern light source bank 3108 comprising one or
more LEDs for generating an aiming pattern. In operation, the terminal
100 can be oriented relatively to the product 3030 by an operator of the
terminal 100 in such manner that the aiming pattern is projected on the
encoded symbol character 3032.

[0026] In another aspect, the optical indicia reading terminal can further
comprise an optical bandpass filter 3110 disposed in an optical pass of
light incident on the image sensor. The optical bandpass filter 3110 can
be configured to pass light of one or more selected ranges of wavelengths
and to attenuate light of wavelengths outside of the selected ranges. In
one embodiment, the optical bandpass filter 3110 can be configured to
pass light of two or more selected ranges of wavelengths and to attenuate
light of wavelengths outside of the selected ranges.

[0027] In the illustrative embodiment of FIG. 3, the optical bandpass
filter 3110 can be disposed between the housing window 63 and the imaging
lens assembly 3100. In another embodiment, the filter module 3110 can be
disposed, for example, but not limited to, between the imaging lens
assembly 3100 and the image sensor 62, at a surface of the imaging lens
assembly 3100, or at a surface of the micro-lens 3077 of the image sensor
62. In a yet another embodiment, the filter module 3110 can be built-in,
for example, but not limited to, into the imaging lens assembly 3100,
into the micro-lens 3077 of the image sensor 62, or into the housing
window 63.

[0028] In one embodiment, the optical bandpass filter 3110 can be
manufactured using one or more multi-layer coatings which can be applied
to a optically transparent substrate.

[0029] In another embodiment, the optical bandpass filter 3110 can be
manufactured using periodic structures which can be formed by a single
material or multiple different materials with repeating features in one
or more dimensions. A skilled artisan would appreciate the fact that
other technologies of manufacturing optical bandpass filter are within
the scope of this disclosure.

[0030] In a further aspect, the optical bandpass filter 3110 can be
described by the following characteristics: [0031] Center Wavelength
(CWL) is the wavelength at the center of the passband; [0032] Full Width
at Half Maximum (FWHM) is the bandwidth at 50% of the maximum
transmission; [0033] peak Transmission (T) is the wavelength of maximum
transmission. [0034] blocking range is the spectral region in which the
filter does not transmit.

[0035] In one embodiment, the CWL of the optical bandpass filter 3110 can
be configured to match the illumination light spectrum. In one
illustrative embodiment shown in FIG. 4, the optical bandpass filter can
have a CWL equal to 635 nm, and FWHM equal to 65 nm to accommodate the
ray angle as well as LED variation (for amber LED with peak wavelength of
624 nm, dominant wavelength of 617 nm, tolerance+7/-5 nm).

[0036] In another embodiment, the optical bandpass filter can include an
additional passband 410 which can be configured, for example, to match a
blue peak of the white light, as shown in FIG. 5. In another embodiment,
the optical bandpass filter can include an additional passband configured
to match the backlight emitting by a screen of a portable communication
device, for example, but not limited to, PDA or cellular phone.

[0037] In a yet another embodiment, the optical bandpass filter can
include two additional passbands 510, 520 which can be configured, for
example, to match a blue and a green peak of the white light, as shown in
FIG. 6.

[0038] In a further aspect, the optical indicia reading terminal 100 can
include various control circuits. Lens assembly 3100 can be controlled
with use of lens assembly control circuit 3114 and the illumination
assembly 3104 comprising illumination pattern light source bank 3106 and
aiming pattern light source bank 3108 can be controlled with use of
illumination assembly control circuit 3116. Filter module 3110 can be
controlled with use of a filter module control circuit 3118, which can be
coupled to the actuator assembly 3112. Lens assembly control circuit 3114
can send signals to lens assembly 3100, e.g., for changing a focal length
and/or a best focus distance of lens assembly 3100. Illumination assembly
control circuit 3116 can send signals to illumination pattern light
source bank 3106, e.g., for changing a level of illumination output.

[0039] In a further aspect, the optical indicia reading terminal 100 can
include various interface circuits for coupling several of the peripheral
devices to system address/data bus (system bus) bus 3120, for
communication with the processor 3088 also coupled to system bus 3120.
The optical indicia reading terminal 100 can include interface circuit
3122 for coupling image sensor timing and control circuit 3084 to system
bus 3120, interface circuit 3124 for coupling the lens assembly control
circuit 3114 to system bus 3120, interface circuit 3126 for coupling the
illumination assembly control circuit 3116 to system bus 3120, interface
circuit 3128 for coupling a display 3130 to system bus 3120, interface
circuit 3132 for coupling a keyboard 3134, a pointing device 3136, and
trigger 3060 to system bus 3120, and interface circuit 3138 for coupling
the filter module control circuit 3118 to system bus 3120.

[0040] In a further aspect, the optical indicia reading terminal 100 can
include one or more I/O interfaces 3140, 3142 for providing communication
with external devices (e.g., a cash register server, a store server, an
inventory facility server, a local area network base station, a cellular
base station). I/O interfaces 3140, 3142 can be interfaces of any
combination of known computer interfaces, e.g., Ethernet (IEEE 802.3),
USB, IEEE 802.11, Bluetooth, CDMA, and GSM, and may couple with
processors, such as interface microcontrollers, and memories to carry out
some or all the functions described herein.

[0041] While the present invention has been described with reference to a
number of specific embodiments, it will be understood that the true
spirit and scope of the invention should be determined only with respect
to claims that can be supported by the present specification. Further,
while in numerous cases herein wherein systems and apparatuses and
methods are described as having a certain number of elements it will be
understood that such systems, apparatuses and methods can be practiced
with fewer than the mentioned certain number of elements. Also, while a
number of particular embodiments have been described, it will be
understood that features and aspects that have been described with
reference to each particular embodiment can be used with each remaining
particularly described embodiment.

[0042] A sample of systems and methods that are described herein follows:

A1. A decodable indicia reading terminal comprising: [0043] a housing
including a housing window; [0044] a multiple pixel image sensor disposed
within said housing; [0045] an imaging lens configured to focus an image
of decodable indicia on said image sensor; [0046] an optical bandpass
filter disposed in an optical path of light incident on said image
sensor, said optical bandpass filter configured to pass light of two or
more selected ranges of wavelengths and to attenuate light of wavelengths
outside of said two or more selected ranges; [0047] an analog-to-digital
(A/D) converter configured to convert an analog signal read out of said
image sensor into a digital signal representative of said analog signal,
said analog signal representative of light incident on said image sensor;
and [0048] a processor configured to output a decoded message data
corresponding to said decodable indicia by processing said digital
signal. A2. The optical indicia reading terminal of A1 configured to
acquire images in a monochrome mode and in a color mode. A3. The optical
indicia reading terminal of A1, wherein said optical bandpass filter is
disposed between said housing window and said imaging lens. A4. The
optical indicia reading terminal of A1, wherein said optical bandpass
filter is disposed said imaging lens assembly and said image sensor. A5.
The optical indicia reading terminal of A1, wherein said optical bandpass
filter is disposed at a surface of said imaging lens assembly. A6. The
optical indicia reading terminal of A1, wherein said multiple pixel image
sensor comprises a micro-lens; and [0049] wherein said optical bandpass
filter is disposed at a surface of said micro-lens. A7. The optical
indicia reading terminal of A1, wherein said optical bandpass filter is
built-in into said imaging lens assembly. A8. The optical indicia reading
terminal of A1, wherein said multiple pixel image sensor comprises a
micro-lens; and [0050] wherein said optical bandpass filter is built-in
into said micro-lens. A9. The optical indicia reading terminal of A1,
wherein said optical bandpass filter is built-in into said housing
window. A10. The optical indicia reading terminal of A1, wherein said
filter comprises a multi-layer coating. A11. The optical indicia reading
terminal of A1, wherein said filter comprises periodic structures. A12.
The optical indicia reading terminal of A1, further comprising one or
more illumination LEDs configured to illuminate a substrate bearing
decodable indicia. A13. The optical indicia reading terminal of A1,
further comprising one or more illumination LEDs having different
spectral characteristics, said one or more illumination LEDs configured
to illuminate a substrate bearing decodable indicia. A14. The optical
indicia reading terminal of A1, further comprising one or more
illumination LEDs, each illumination LED of said one or more illumination
LEDs comprising one or more dies having different spectral
characteristics; [0051] wherein said one or more illumination LEDs are
configured to illuminate a substrate bearing decodable indicia. A15. The
optical indicia reading terminal of A1, further comprising one or more
illumination LEDs configured to illuminate a substrate bearing decodable
indicia, by emitting light having an illumination light spectrum; [0052]
wherein said illumination light spectrum varies at different areas of
said substrate. A16. The optical indicia reading terminal of A1, further
comprising one or more illumination LEDs configured to illuminate said
substrate, by emitting light having an illumination light spectrum;
[0053] wherein a center wavelength of said optical bandpass filter is
configured to match said illumination light spectrum. A17. The optical
indicia reading terminal of A1, wherein said optical bandpass filter
includes a passband configured to match a backlight emitted by a portable
communication device. A18. The optical indicia reading terminal of A1,
wherein said housing is provided by a hand held housing. A19. The optical
indicia reading terminal of A1, wherein said housing is provided by a
point-of-sale workstation housing. A20. The optical indicia reading
terminal of A1 wherein said housing is provided by a presentation
housing.

[0054] While the present invention has been described with reference to a
number of specific embodiments, it will be understood that the true
spirit and scope of the invention should be determined only with respect
to claims that can be supported by the present specification. Further,
while in numerous cases herein wherein systems and apparatuses and
methods are described as having a certain number of elements it will be
understood that such systems, apparatuses and methods can be practiced
with fewer than or greater than the mentioned certain number of elements.
Also, while a number of particular embodiments have been described, it
will be understood that features and aspects that have been described
with reference to each particular embodiment can be used with each
remaining particularly described embodiment.